[Dovecot] what best for anti-spam filter?

[Markus Schönhaber]

24.07.2012 11:57, Arnaud Abélard:

> - With greylisting we aren't rejecting potentially spammy mails, we are 
> rejecting misbehaving servers. That's important, legally speaking. We 
> could be in trouble if we rejected an important mail by mistake when our 
> server actually accepted it.

That's something which is not greylisting-specific at all. You must not
accept mail you are unwilling or unable to deliver - ever!
Creating bounces will make you a source of backscatter and get you
blacklisted, eventually.
("Outgoing" mail is a different matter, of course)

But that doesn't mean that greylisting is the only means for fighting
spam that is compliant to the above rule. It's, for example, not
uncommon to have things like milters or pre-queue filters pipe the
incoming mail through a spam checker and accept or reject the mail -
during the SMTP dialogue - depending on the result of the check.

-- 
Regards
  mks